Abstract

Assessment of Sputum Quality and Its Importance in the Rapid Diagnosis of Pulmonary Tuberculosis

Background: Sputum smear microscopy is the gold standard
method for the diagnosis of pulmonary tuberculosis. Poor
quality of sputum might result in missing the diagnosis. In
the present study, we aimed at assessing the microscopic
quality of sputum with reference to the number of pus cells
and squamous epithelial cells observed on Gram’s stained
smears as an indirect marker.

Methods: A total number of 200 sputum specimens were
collected from 91 suspected TB patients and were subjected
to ZN staining, LJ culture to out the acid fast bacilli; gram's
staining and Blood agar culture for lower respiratory tract
infectious organisms.

Results: Of 200 specimens, 59 from 28 patients were
positive for acid fast bacilli. Based on the number of pus
cells and squamous epithelial cells, specimens were
categorized into four groups. Group 1 (sputum) was
significantly associated with ZN smear positivity and Group
4 (saliva) with smear negativity (p<0.001). The specimens
with >25 pus cells per field (including group 1&2) were
significantly associated with ZN and LJ culture positivity
(p<0.001), whereas the presence of >10 SE cells was not
associated with smear negativity (p>0.1).

Conclusion: Group 1 (sputum) was associated with ZN
smear positivity and Group 4 (saliva) was associated with
smear negativity. Pus cells were proved as an indirect
marker for sputum quality assessment. Sputum samples
with more number of pus cells (regardless of the group)
were significantly associated with ZN and LJ culture
positivity. So, proper patient education before obtaining the
sputum sample and timely monitoring during collection
time can be helpful to obtain good quality sputum to
enhance the TB disease diagnostic yield.